On December 20, 1860, when it became clear that Lincoln would be the next president, South Carolina became the first state to declare its secession from the Union.
The reason, slavery.

DECLARATION OF THE IMMEDIATE CAUSES WHICH INDUCE AND JUSTIFY THE SECESSION OF SOUTH CAROLINA FROM THE FEDERAL UNION.

The people of the State of South Carolina, in convention assembled, on the 26th day of April, A.D., 1852, declared that the frequent violations of the constitution of the United States by the federal government, and its encroachments upon the reserved rights of the states, fully justified this state in then withdrawing from the Federal Union; but in deference to the opinions and wishes of the other slaveholding states, she forbore at that time to exercise this right. Since that time, these encroachments have continued to increase, and further forbearance ceases to be a virtue.
And now the State of South Carolina having resumed her separate and equal place among nations, deems it due to herself, to the remaining United States of America, and to the nations of the world, that she should declare the immediate causes which have led to this act.
In the year 1765, that portion of the British Empire embracing Great Britain, undertook to make laws for the government of that portion composed of the thirteen American colonies. A struggle for the right of self-government ensued, which resulted, on the 4th of July, 1776, in a Declaration, by the Colonies, "that they are, and of right ought to be, FREE AND INDEPENDENT STATES: and that as free and independent states, they have full power to levy war, conclude peace, contract alliances, establish commerce, and to do all other acts and things which independent States may of right do."
They further solemnly declared that whenever any "form of government becomes destructive of the ends for which it was established, it is the right of the people to alter or abolish it, and to institute a new government." Deeming the government of Great Britain to have become destructive of these ends, they declared that the colonies "are absolved from all allegiance to the British crown, and that all political connection between them and the State of Great Britain is, and ought to be totally dissolved."
In pursuance of this Declaration of Independence, each of the thirteen States proceeded to exercise its separate sovereignty; adopted for itself a constitution, and appointed officers for the administration of government in all its departments legislative, executive and judicial. For purposes of defense, they united their arms and their counsels; and, in 1778 they entered into a league known as the articles of confederation, whereby they agreed to entrust the administration of their external relations to a common agent, known as the Congress of the United States, expressly declaring in the first article, "that each state retains its sovereignty, freedom and independence, and every power, jurisdiction and right which is not, by this confederation, expressly delegated to the United States in Congress assembled."
Under this confederation the war of the revolution was carried on, and on the 3d September, 1783, the contest ended, and a definite treaty was signed by Great Britain, in which she acknowledged the independence of the colonies in the following terms:
"ARTICLE 1 His Britanic Majesty acknowledges the said United States, viz: New Hampshire, Massachusetts Bay, Rhode Island and Providence Plantations, Connecticut, New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, North Carolina, South Carolina and Georgia, to be FREE, SOVEREIGN AND INDEPENDENT STATES; that he treats with them as such; and for himself, his heirs and successors, relinquishes all claims to the government, propriety and territorial rights of the same and every part thereof."
Thus were established the two great principles asserted by the colonies, namely: the right of a state to govern itself; and the right of a people to abolish a government when it becomes destructive of the ends for which it was instituted. And concurrent with the establishment of these principles, was the fact that each colony became and was recognized by the mother country as a FREE, SOVEREIGN AND INDEPENDENT STATE.
In 1787, deputies were appointed by the States to revise the articles of confederation, and on 17th of September, 1787, these deputies recommended for the adoption of the states, the articles of union known as the Constitution of the United States.
The parties to whom this Constitution was submitted, were the several sovereign states; they were to agree or disagree, and when nine of them agreed, the compact was to take effect among those concurring; and the general government, as the common agent, was then invested with their authority.
If only nine of the thirteen states had concurred, the other four would have remained as they then were separate, sovereign states, independent of any of the provisions of the constitution. In fact, two of the states did not accede to the constitution until long after it had gone into operation among the other eleven; and during that interval they each exercised the functions of an independent nation.
By this constitution, certain duties were imposed upon the several states, and the exercise of certain of their powers was restrained, which necessarily implied their continued existence as sovereign states. But to remove all doubt, an amendment was added, which declared that the powers not delegated to the United States by the constitution, nor prohibited by it to the states, are reserved to the states, respectively, or to the people. On 23d May, 1788, South Carolina, by a convention of her people, passed an ordinance assenting to this constitution, and afterwards altered her own constitution, to conform herself to the obligations she had undertaken.
Thus was established, by compact between the states, a government, with defined objects and powers, limited to the express words of the grant. This limitation left the whole remaining mass of power subject to the clause reserving it to the states or to the people, and rendered unnecessary any specification of reserved rights.
We hold that the government thus established is subject to the two great principles asserted in the Declaration of Independence; and we hold further, that the mode of its formation subjects it to a third fundamental principle, namely: the law of compact. We maintain that in every compact between two or more parties the obligation is mutual; that the failure of one of the contracting parties to perform a material part of the agreement, entirely releases the obligation of the other; and that where no arbiter is provided, each party is remitted to his own judgment to determine the fact of failure, with all its consequences.
In the present case, that fact is established with certainty. We assert that fourteen of the states have deliberately refused for years past, to fulfil their constitutional obligations, and we refer to their own statutes for the proof.
The constitution of the United States, in its 4th article, provides as follows:
"No person held to service or labor in one state, under the laws thereof, escaping into another, shall, in consequence of any law or regulation therein, be discharged from such service or labor, but shall be delivered up on claim of the party to whom such service or labor may be due."
This stipulation was so material to the compact, that without it that compact would not have been made. The greater number of the contracting parties held slaves, and they had previously evinced their estimate of the value of such a stipulation by making it a condition in the ordinance for the government of the territory ceded by Virginia, which now composes the states north of the Ohio river.
The same article of the constitution stipulates also for rendition, by the several states, of fugitives from justice from the other states.
The general government, as the common agent, passed laws to carry into effect these stipulations of the states. For many years these laws were executed. But an increasing hostility on the part of the non-slaveholding states to the institution of slavery has led to a disregard of their obligations, and the laws of the general government have ceased to effect the objects of the Constitution. The States of Maine, New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, New York, Pennsylvania, Illinois, Indiana, Michigan, Wisconsin and Iowa, have enacted laws which either nullify the acts of Congress or render useless any attempt to execute them. In many of these states the fugitive is discharged from service or labor claimed, and in none of them has the state government complied with the stipulation made in the constitution. The State of New Jersey, at an early day, passed a law in conformity with her constitutional obligation; but the current of anti-slavery feeling has led her more recently to enact laws which render inoperative the remedies provided by her own law and by the laws of Congress. In the State of New York even the right of transit for a slave has been denied by her tribunals; and the States of Ohio and Iowa have refused to surrender to justice fugitives charged with murder, and with inciting servile insurrection in the State of Virginia. Thus the constituted compact has been deliberately broken and disregarded by the non-slaveholding states, and the consequence follows that South Carolina is released from her obligation.
The ends for which this constitution was framed are declared by itself to be "to form a more perfect union, establish justice, insure domestic tranquillity, provide for the common defence, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity."
These ends it endeavored to accomplish by a federal government, in which each state was recognized as an equal, and had separate control over its own institutions. The right of property in slaves was recognized by giving to free persons distinct political rights, by giving them the right to represent, and burthening them with direct taxes for three-fifths of their slaves; by authorizing the importation of slaves for twenty years, and by stipulating for the rendition of fugitives from labor.
We affirm that these ends, for which this Government was instituted, have been defeated, and the government itself has been made destructive of them by the action of the non-slaveholding states. Those states have assumed the right of deciding upon the propriety of our domestic institutions; and have denied the rights of property established in fifteen of the states and recognized by the constitution; they have denounced as sinful the institution of slavery; they have permitted the open establishment among them of societies, whose avowed object is to disturb the peace and to eloign the property of the citizens of other states. They have encouraged and assisted thousands of our slaves to leave their homes, and those who remain have been incited by emissaries, books and pictures to servile insurrection.
For twenty-five years this agitation has been steadily increasing, until it has now secured to its aid the power of the common government. Observing the forms of the constitution, a sectional party has found within that article establishing the executive department the means of subverting the constitution itself. A geographical line has been drawn across the Union, and all the states north of that line have united in the election of a man to the high office of President of the United States, whose opinions and purposes are hostile to slavery. He is to be entrusted with the administration of the common government, because he has declared that that "government cannot endure permanently half slave, half free," and that the public mind must rest in the belief that slavery is in the course of ultimate extinction.
This sectional combination for the subversion of the constitution, has been aided in some of the states by elevating to citizenship, persons, who, by the supreme law of the land, are incapable of becoming citizens; and their votes have been used to inaugurate a new policy, hostile to the South, and destructive of its peace and safety.
On the 4th of March next this party will take possession of the government. It has announced that the South shall be excluded from the common territory; that the judicial tribunals shall be made sectional, and that a war must be waged against slavery until it shall cease throughout the United States.
The guaranties of the constitution will then no longer exist; the equal rights of the states will be lost. The slaveholding states will no longer have the power of self-government, or self-protection, and the federal government will have become their enemy. Sectional interest and animosity will deepen the irritation, and all hope of remedy is rendered vain, by the fact that public opinion at the North has invested a great political error, with the sanctions of a more erroneous religious belief. We, therefore, the people of South Carolina, by our delegates, in convention assembled, appealing to the Supreme Judge of the world for the rectitude of our intentions, have solemnly declared that the union heretofore existing between this state and the other states of North America, is dissolved, and that the State of South Carolina has resumed her position among the nations of the world, as a separate and independent state, with full power to levy war, conclude peace, contract alliances, establish commerce, and to do all other acts and things which independent states may of right do.